Abstract The Pyrenees are the main source of water for a large region in Southern Europe. In recent decades, streamflow and snow accumulation in these mountains have decreased, and climate models predict that further reductions in water will threaten the sustainability of downstream regions. This article presents a cascading multi-model and multi-scenario approach to assess how future climate change may affect the hydrology and water management of Pyrenees-dependent systems. In particular, we combined future climate projections and management scenarios and applied them to the Gallego-Cinca River System in the Ebro River Basin of Spain. We developed a hydrologic model for the headwaters of this system (the source of most of the water), and then used a management model to simulate reservoir operation and water allocation among the different agricultural demand units of this system, the largest irrigated region in Spain. We assessed future headwater streamflow for 22 climate models, and translated this climate signal into a management model by using a delta change approach. Finally, we evaluated the performance and sustainability of the system with indicators based on the frequency, duration, and magnitude of the supply deficit. The results show that use of the current planned management scenarios will threaten to the system’s future sustainability, especially for irrigated agriculture. These results indicate a need to revise current water resource planning strategies in this region, and to establish long-term, robust, and sustainable measures for adaptation to climate change.

中文翻译：

---

气候变化下大型水资源系统的长期可持续性：级联建模方法

摘要 比利牛斯山脉是南欧大片地区的主要水源。近几十年来，这些山区的溪流和积雪已经减少，气候模型预测水的进一步减少将威胁到下游地区的可持续性。本文提出了一种级联多模型和多情景方法，以评估未来气候变化如何影响依赖比利牛斯山脉的系统的水文和水资源管理。特别是，我们将未来气候预测和管理情景结合起来，并将它们应用于西班牙埃布罗河流域的加列戈-辛卡河系统。我们为该系统的源头（大部分水的来源）开发了一个水文模型，然后使用管理模型模拟该系统（西班牙最大的灌溉地区）的不同农业需求单位之间的水库运行和水资源分配。我们评估了 22 个气候模型的未来源头流量，并通过使用三角洲变化方法将此气候信号转化为管理模型。最后，我们使用基于供应短缺的频率、持续时间和幅度的指标来评估系统的性能和可持续性。结果表明，使用当前计划的管理方案将威胁到系统未来的可持续性，尤其是灌溉农业。这些结果表明需要修改该地区当前的水资源规划战略，并制定长期、稳健和可持续的适应气候变化的措施。